This application is a continuation of International Application No. PCT/JP00/01047, filed Feb. 24, 2000, which claims the benefit of Japanese Patent Application No. 11-046875, filed Feb. 24, 1999.
The present invention relates to an electron beam apparatus and an image forming apparatus, particularly to an electron beam apparatus and an image forming apparatus having a spacer, and more particularly to an electron beam apparatus and an image forming apparatus having an antistatic film.
Up to now, as the electron emitting elements, there have been known a hot cathode element and a cold cathode element. As the cold cathode element of those elements, there have been known, for example, a surface conduction type electron emission element, a field emission element (hereinafter referred to as xe2x80x9cFE typexe2x80x9d), a metal/insulating layer/metal type emission element (hereinafter referred to as xe2x80x9cMIM typexe2x80x9d), etc.
As the surface conduction type electron emission elements, there have been known, for example, an example disclosed in Radio Eng. Electron Phys., 10, 1290 (1965) by M. I. Elinson, or other examples which will be described later.
The surface conduction type electron emission element utilizes a phenomenon in which electron emission occurs by allowing a current to flow into a small-area thin film formed on a substrate in parallel to a film surface. As the surface conduction type electron emission element, there have been reported a surface conduction type electron emission element using an SnO2 thin film by the above-mentioned Elinson, a surface conduction type electron emission element using an Au thin film [G. Dittmer: xe2x80x9cThin Solid Filmsxe2x80x9d, 9,317 (1972)], a surface conduction type electron emission element using an In2O3/SnO2 thin film [M. Hartwell and C. G. Fonstad: xe2x80x9cIEEE Trans. ED Conf.xe2x80x9d, 519 (1975)], a surface conduction type electron emission element using a carbon thin film [xe2x80x9cVapor Vacuum,xe2x80x9d Vol. 26, No. 1, p22 (1983), by Hisashi Araki, et al.], etc.
As a typical example of those surface conduction type electron emission elements, a plan view of the above-mentioned element by M. Hartwell is shown in FIG. 27. In FIG. 27, reference numeral 3001 denotes a substrate, and reference numeral 3004 denotes an electrically conductive film that is made of a metal oxide formed through sputtering. The electrically conductive film 3004 is formed in an H-shaped plane as shown in FIG. 27. An energizing process called xe2x80x9cenergization formingxe2x80x9d which will be described later is conducted on the electrically conductive thin film 3004 to form an electron emission portion 3005. In FIG. 27, an interval L is set to 0.5 to 1 [mm], and W is set to 0.1 [mm]. For convenience of showing in the figure, the electron emission portion 3005 is shaped in a rectangle in the center of the electrically conductive thin film 3004. However, this shape is schematic and does not faithfully express the position and the configuration of the actual electron emission portion.
In the above-mentioned surface conduction type electron emission elements including the element proposed by M. Hartwell, et al., the electron emission portion 3005 is generally formed on the electrically conductive film 3004 through the energizing process which is called xe2x80x9cenergization formingxe2x80x9d before the electron emission is conducted. In other words, the energization forming is directed to a process in which a constant d.c. voltage or a d.c. voltage that steps up at a very slow rate such as about 1 V/min is applied to both ends of the electrically conductive film 3004 so that the electrically conductive film 3004 is electrified, to thereby locally destroy, deform or affect the electrically conductive film 3004, thus forming the electron emission portion 3005 which is in an electrically high-resistant state. A crack occurs in a part of the electrically conductive film 3004 which has been locally destroyed, deformed or affected. In the case where an appropriate voltage is applied to the electrically conductive thin film 3004 after the above energization forming, electrons are emitted from a portion close to the crack.
Examples of the FE type have been known from xe2x80x9cField Emissionxe2x80x9d of Advance in Electron Physics, 8, 89 (1956) by W. P. Dyke and W. W. Dolan, xe2x80x9cPhysical Properties of Thin-Film Field Emission Cathodes with Molybdenum conesxe2x80x9d of J. Appl. Phys., 47,5248 (1976), by C. A. Spindt, etc.
As a typical example of the element structure of the FE element, FIG. 28 shows a cross-sectional view of the elements made by the above-mentioned C. A. Spindt, et al. In this figure, reference numeral 3010 denotes a substrate, 3011 is an emitter wiring made of an electrically conductive material, 3012 is an emitter cone, 3013 is an insulating layer, and 3014 is a gate electrode. The element of this type is so designed as to apply an appropriate voltage between the emitter cone 3012 and the gate electrode 3014 to produce electric field emission from a leading portion of the emitter cone 3012.
Also, as another element structure of the FE type, there is an example in which an emitter and a gate electrode are disposed on a substrate substantially in parallel with the substrate plane without using a laminate structure shown in FIG. 28.
Also, as an example of the MIM type, there has been known, for example, xe2x80x9cOperation of Tunnel-Emission Devices,xe2x80x9d J. Appl. Phys., 32,646 (1961) by C. A. Mead, etc. A typical example of the element structure of the MIM type is shown in FIG. 29. FIG. 29 is a cross-sectional view, and in the figure, reference numeral 3020 denotes a substrate, 3021 is a lower electrode made of metal, 3022 is a thin insulating layer about 100 [xc3x85] in thickness, and 3023 is an upper electrode made of metal about 80 to 300 [xc3x85] in thickness. In the MIM type, an appropriate voltage is applied between the upper electrode 3023 and the lower electrode 3021, to thereby produce electron emission from the surface of the upper electrode 3023.
The above-mentioned cold cathode element does not require a heater for heating because it can obtain electron emission at a low temperature as compared with the hot cathode element. Accordingly, the cold cathode element is simpler in structure than the hot cathode element and can prepare a fine element. Also, in the cold cathode element, even if a large number of elements are disposed on the substrate with a high density, a problem such as heat melting of the substrate is difficult to occur. Further, the cold cathode element is advantageous in that a response speed is high which is different from the heat cathode element which is low in the response speed because it operates due to heating by the heater.
For the above-mentioned reasons, a study for applying the cold cathode elements has been extensively conducted.
For example, the surface conduction type electron emission element has the advantage that a large number of elements can be formed on a large area since it is particularly simple in structure and easy in manufacture among the cold cathode elements. For that reason, a method in which a large number of elements are arranged and driven has been studied as disclosed in Japanese Patent Application Laid-Open No. 64-31332 by the present applicant.
Also, as the application of the surface conduction type electron emission element, for example, an image display device, an image forming apparatus such as an image recording device, a charge beam source, and so on have been studied. In particular, as the application to the image display device, there has been studied an image display device using the combination of the surface conduction type electron emission element with a phosphor that emits light by irradiation of an electron beam as disclosed in for example U.S. Pat. No. 5,066,883 by the present applicant, Japanese Patent Application Laid-Open No. 2-257551, and Japanese Patent Application Laid-Open No. 4-28137. In the image display device using the combination of the surface conduction type electron emission element with the phosphor, the characteristic superior to the conventional other image display devices is expected. For example, even as compared with the liquid crystal display device which has been spread in recent years, the above image display device is excellent in that no back light is required because it is of the self light emitting type and the angle of visibility is broad.
Also, a method in which a large number of FE type elements are disposed and driven is disclosed in, for example, U.S. Pat. No. 4,904,895 by the present applicant. Also, as an example of applying the FE type to the image display device, there has been known, for example, a plate type image display device reported by R. Meyer [R. Meyer: xe2x80x9cRecent Development on Micro-Tips Display at LETIxe2x80x9d, Tech. Digest of 4th Int. Vacuum Microelectronics Conf., Nagahama, pp. 6 to 9 (1991)].
Also, an example in which a large number of MIM type elements are arranged and applied to an image display device is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-55738 by the present applicant.
Among the image forming apparatuses using the above-mentioned electron emission element, attention has been paid to the flat type image display device thin in depthwise as a replacement of the CRT type image display device since the space is saved and the weight is light.
FIG. 30 is a perspective view showing an example of a display panel portion which forms a plane-type image display device, in which a part of the panel is cut off in order to show the internal structure.
In FIG. 30, reference numeral 3115 denotes a rear plate, 3116 a side wall, 3117 a face plate, and the rear plate 3115, the side wall 3116 and the face plate 3117 form an envelope (hermetic container) for maintaining the interior of the display panel in a vacuum state. The rear plate 3115 is fixed with a substrate 3111, and Nxc3x97M cold cathode elements 3112 are formed on the substrate 3111 (N and M are positive integers of equal to or larger than 2 or more and appropriately set in accordance with the target number of display pixels). Also, the Nxc3x97M cold cathode elements 3112 are wired by M row wirings 3113 and N column wirings 3114 as shown in FIG. 30. A portion made up of the substrate 3111, the cold cathode elements 3112, the row wirings 3113 and the column wirings 3114 is called xe2x80x9cmultiple electron beam sourcexe2x80x9d. Also, at least in portions where the row wirings 3113 and the column wirings 3114 cross each other, an insulating layer (not shown) between both of the wirings is formed to keep electric insulation.
A lower surface of the face plate 3117 is formed with a fluorescent film 3118 formed of a phosphor on which phosphors (not shown) of three primary colors consisting of red (R), green (G) and blue (B) are separately painted. Also, black material (not shown) are disposed between the respective color phosphors which form the fluorescent film 3118, and a metal back 3119 made of Al or the like is formed on a surface of the fluorescent film 3118 on the rear plate 3115 side.
Dx1 to Dxm and Dy1 to Dyn and Hv are electric connection terminals with a hermetic structure provided for electrically connecting the display panel to an electric circuit not shown. Dx1 to Dxm are electrically connected to the row wirings 3113 of the multiple electron beam source, Dy1 to Dyn are electrically connected to the column wirings 3114 of the multiple electron beam source, and Hv is electrically connected to the metal back 3119, respectively.
Also, the interior of the above hermetic container is maintained in a vacuum state of about 10xe2x88x926 Torr, and there is required means for preventing the deformation or destruction of the rear plate 3115 and the face plate 3117 due to a pressure difference between the interior of the hermetic container and the external, as a display area of the image display device increases. In a method of thickening the rear plate 3115 and the face plate 3117, not only does the weight of the image display device increase, but also a distortion of an image or a parallax occurs when viewing the display device from an oblique direction. On the contrary, in FIG. 30, there is provided a structure support (called xe2x80x9cspacerxe2x80x9d or xe2x80x9cribxe2x80x9d) 3120 which is formed of a relatively thin glass substrate for supporting the atmospheric pressure. With this structure, a space of normally sub mm to several mm is kept between the substrate 3111 on which the multiple beam electron source is formed and the face plate 3117 on which the fluorescent film 3118 is formed, and the interior of the hermetic container is maintained in a high vacuum state as described above.
In the image display device using the display panel as described above, when a voltage is applied to the respective cold cathode elements 3112 through the container external terminals Dx1 to Dxm and Dy1 to Dyn, electrons are emitted from the respective cold elements 3112. At the same time, with the application of a high voltage of several hundreds [V] to several [kV] to the metal back 3119 through the container external terminal Hv, the above emitted electrons are accelerated and allowed to collide with an inner surface of the face plate 3117. As a result, the phosphors of the respective colors which form the fluorescent film 3118 are excited and emit light, thus displaying an image.
An object of the present invention is to realize a preferred electron beam apparatus.
That is, an electron beam apparatus according to one aspect of the present invention is structured as follows:
An electron beam apparatus comprising a hermetic container, an electron source disposed within the above hermetic container, and a spacer; wherein the above spacer includes at least a region where a layer containing fine particles exist, a sheet resistance measured at the surface of the above region of the above spacer is 107 xcexa9/xe2x96xa1 or more, the above fine particles are sized equal to or lower than 1000 xc3x85 in the average diameter of the particles, and includes at least metal elements.
The spacer may maintain the configuration of the hermetic container. For example, the spacer may serve as a part of the hermetic container as with a frame. Also, the present invention is more preferably applicable to a structure having the spacer disposed in the hermetic space within the hermetic container.
In particular, the present invention is particularly effective to a case in which the hermetic container includes plate-shaped members that face each other, the height of the spacer that maintains an interval between the members that face each other is equal to or less than {fraction (1/50)} or less of the main length (diagonal length of the hermetic space in the case where the hermetic space is square) in a direction orthogonal to a heightwise direction of the above spacer in the hermetic space formed between the members that face each other, more particularly in a case where the height of the spacer is equal to or less than {fraction (1/100)} or less.
If the average particle diameter is set equal to or less than 1000 xc3x85, the deviation of the fine particles, or the deviation of the secondary particles due to the coagulated fine particles may be suppressed. Also, the electric characteristic of the layer including the fine particles is stabilized. In particular, in the case of using a binder, the degree of dispersion of the fine particles within the binder is readily controlled. If the fine particles include metal elements, the electric conductivity (resistance) can be stabilized. The metal elements may be made into a compound with other elements and may preferably form metal oxide or metal nitride. The average particle diameter may be set equal to or less than 200 xc3x85, or more preferably equal to or less than 100 xc3x85.
It is desirable that the sheet resistance measured at the surface of the above region of the spacer is 1014 xcexa9/xe2x96xa1 or less.
In the above invention, the layer including the above fine particles may be disposed on a base substance that constitutes the above spacer. It is not necessary to expose the layer including the fine particles from the surface of the spacer, and another layer may be further disposed on the layer including the fine particles. In this case, the sheet resistance includes contributions of the resistance of the layer including the fine particles and the resistance of another layer. The use of the base substance of the spacer facilitates the manufacture and also facilitates the control of the electric conductivity (resistance). It is preferable that the base substance of the spacer is made of insulating material. Further, it is unnecessary that the region that satisfies the above conditions of the present invention exists on the entire surface of the spacer.
Also, in the above respective present inventions, the layer including the fine particles according to the respective present inventions may be variously structured in such a case that the layer including the above fine particles is made up of the fine particles and gaps which are disposed between the fine particles and filled with other solid such as binders, or in such a case that the layer including the above fine particles is made up of the fine particles and gaps which are disposed between the fine particles and not filled with the solid. The volume percentage of the fine particles in the layer may be equal to or less than 30%.
Also, in the above respective present inventions, it is preferable that the layer including the above fine particles includes the above fine particles and the binder. The binder preferably includes inorganic compound.
Further, in the above respective present inventions, it is preferable that the average particle diameter of the above fine particles is set equal to or less than 0.1 times of the thickness of the layer including the above fine particles. The average particle diameter may be more preferably set equal to or less than 0.05 times, and most preferably set equal to or less than 0.02 times.
Still further, in the above respective present inventions, it is preferable that the above fine particles include metal oxide or metal nitride, and also it is preferable that the above fine particles include elements of group IIIB or group VB, and also it is preferable that the above fine particles include Sb or P.
Still further, in the above respective present inventions, it is more preferable that the layer including the above fine particles has a rough surface as shown in the embodiments later. In the case where another layer is disposed on the layer including the fine particles, it is preferable that the other layer has a rough surface. It is preferable that the surface roughness of the spacer surface in the region where the layer including the fine particles exists according to the respective present inventions is larger than 100 xc3x85.
Also, an electron beam apparatus according to the present invention is as follows:
An electron beam apparatus comprising a hermetic container, an electron source disposed within the above hermetic container, and a spacer; wherein the above spacer includes at least a region where a layer containing fine particles exist, a sheet resistance measured at the surface of the above region of the above spacer is 107 xcexa9/xe2x96xa1 or more, and the above fine particles are sized equal to or less than 200 xc3x85 in the average diameter of the particles and are fine particles having electric conductivity.
Further, an electron beam apparatus according to the present invention in this application is as follows:
An electron beam apparatus comprising a hermetic container, an electron source disposed within the above hermetic container, and an antistatic film disposed within the above hermetic container; wherein the above hermetic preventing film includes at least a layer including fine particles, a sheet resistance measured at the surface of the above antistatic film is 107 xcexa9/xe2x96xa1 or more, and the above fine particles are sized equal to or less than 1000 xc3x85 in the average diameter of the particles and include fine particles containing at least metal elements.
Still further, an electron beam apparatus according to the present invention in this application is as follows:
An electron beam apparatus comprising a hermetic container, an electron source disposed within the above hermetic container, and an antistatic film disposed within the above hermetic container; wherein the above antistatic film includes at least a layer containing fine particles, a sheet resistance measured at the surface of the above antistatic film is 107 xcexa9/xe2x96xa1 or more, and the above fine particles are sized equal to or less than 200 xc3x85 in the average diameter of the particles and include electrically conductive fine particles.
Further, in this application, the present invention includes an image forming apparatus comprising the above-mentioned respective electron beam apparatuses and an image forming member that forms an image by irradiation of electrons from an electron source provided in the above electron beam apparatus. The image forming member may be made up of, for example, a phosphor.